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  <title>Document</title>
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<body>
  <div>promise</div>
  <script>
    var p = new Promise((r, e) => {
      r('123')
    })
    console.log(2222)
    let result = p.then(res => {
      console.log(res)
      // 1
      // throw 'sdfsdf'
      // 2
      // return 'abc'
      // 3 
      return new Promise((r,e)=>{
        // r('return is promise resolev')
        e('error')
      })
    })
    console.log(result)
    result.then(res => {
      console.log(res)
    })
  </script>
</body>

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